The Legend of Zelda: The Wind Waker - Poe

Poes are ghost-like enemies that are immune to attacks until they are exposed to sunlight, either from a light source, the Mirror Shield, or Medli's harp. Once they are, almost any weapon can be used to take them out. However, Poes can possess Link, reversing his controls for a short time. Link can remove this curse by either finding some sunlight or by just waiting for it to wear off on its own.